Sepsis is a major cause of morbidity and mortality in humans and other animals. In the United States, sepsis is the second leading cause of death in intensive care units among patients with non-traumatic illnesses. It is also the leading cause of death in young livestock, affecting 7.5-29% of neonatal calves, and is a common medical problem in neonatal foals. Despite the major advances of the past several decades in the treatment of serious infections, the incidence and mortality due to sepsis continues to rise.
Sepsis results from the systemic invasion of microorganisms into blood and can present two distinct problems. First, the growth of the microorganisms can directly damage tissues, organs, and vascular function. Second, toxic components of the microorganisms can lead to rapid systemic inflammatory responses that can quickly damage vital organs and lead to circulatory collapse (i.e., septic shock) and, often times, death.
There are three major types of sepsis characterized by the type of infecting organism. For example, gram-negative sepsis is the most frequently isolated (with a case fatality rate of about 35%). The majority of these infections are caused by Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa. Gram-positive pathogens such as the Staphylococci and Streptococci are the second major cause of sepsis. The third major group includes fungi, with fungal infections causing a relatively small percentage of sepsis cases, but with a high mortality rate; these types of infections also have a higher incidence in immuno-compromised patients.
Many patients with septicemia or suspected septicemia exhibit a rapid decline over a 24-48 hour period. It has been reported that patients with septic shock require adapted treatment in less than 6 hours in order to benefit from antimicrobial therapy. Thus, rapid, reliable and sensitive diagnostic and treatment methods are essential for effective patient care. In addition, the ability to rapidly detect with high sensitivity pathogens for non-medical applications, such as food, water, and/or environmental testing would also have great value, in addition to medical applications, e.g., for preventing infections and sepsis in the population. Hence, there remains a need for improved reagents and techniques that can not only provide high-affinity binding for capture of microbes (e.g., pathogens) and/or microbial matter, but can also provide high-sensitivity detection capability to detect the presence of microbes (e.g., pathogens) and/or microbial matter.